CONCENTRATING SOLAR POWERED TRANSCRITICAL CO2 POWER GENERATION CYCLE FOR THE UNION TERRITORY OF LADAKH, INDIA

Abstract

High solar irradiation, cloud-free dry climate, abundant barren land, and low ambient temperature make the Union Territory of Ladakh, India, suitable for concentrating solar thermal power (CSP) plants. The present study comprehensively analyzes a 5 MW transcritical CO<sub>2</sub> Rankine cycle power tower CSP plant. Low ambient temperature of the region allows transcritical operation, which provides high cycle efficiency. The study focuses on five aspects: solar field and thermal energy storage (TES), thermodynamic cycle simulation, turbomachines, and off-design performance analysis. Modeling and optimization of the solar field are undertaken to capture the diurnal and annual variations of direct normal irradiation levels using System Advisor Model open source software. Molten salt TES is integrated to overcome the dynamic variations of solar energy by providing stable operations and additional hours. The effect of storage sizes, starting from no storage to 12 hours, on the solar field size and specifications is also assessed. An in-house algorithm is developed for thermodynamic cycle optimization, exergy analysis, and off-design operations. The turbomachines of the cycle are designed using in-house meanline codes, and 3D CFD simulations are conducted for efficiency estimations. The effects of ambient temperature variations on the low side saturation pressure, cycle efficiency, and power output are evaluated. The proposed plant offers annual optical efficiency of 54.1%, thermal efficiency of 36.5%, and overall efficiency of 19.7%.